clarify supported nodejs versions

[micalevisk]

Is your feature request related to a problem? Please describe.

I don't know if I can safely use @lumigo/tracer package with my nodejs

Describe the solution you'd like

for better DX on using this package, I'd suggest you to add the following to package.json:

  "engines": {
    "node": ">=16"
  },

Describe alternatives you've considered

clarify at https://docs.lumigo.io/docs/nodejs which is the minimum supported nodejs version

[pappnase99]

Even more relevant now that Node v22 became the current LTS version last week.